Spiritbonding has always been in games. However, unlike in most games, this game actually uses that to produce useful, sellable items, for the most part, called materia.

Now honestly, I do wish that certain items could be converted into materia, because they are otherwise considered worthless if they get even 1% of spiritbonding on them.

But really, that's literally the only way I see your solution being fixed, by allowing all tradeable gear to be convertible into materia once it reaches 100% spiritbond, not just the White and Pink items.